diff --git a/Demonstration/Demonstration.vcxproj b/Demonstration/Demonstration.vcxproj
index 6f29ba4..b3d1ca5 100644
--- a/Demonstration/Demonstration.vcxproj
+++ b/Demonstration/Demonstration.vcxproj
@@ -142,6 +142,7 @@
     </Link>
   </ItemDefinitionGroup>
   <ItemGroup>
+    <ClCompile Include="book.c" />
     <ClCompile Include="main.c" />
   </ItemGroup>
   <ItemGroup>
@@ -152,6 +153,9 @@
       <Project>{43c12dd0-611c-43ee-82f4-f25b33eed30b}</Project>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="book.h" />
+  </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
diff --git a/Demonstration/Demonstration.vcxproj.filters b/Demonstration/Demonstration.vcxproj.filters
index 87fef6a..73f3369 100644
--- a/Demonstration/Demonstration.vcxproj.filters
+++ b/Demonstration/Demonstration.vcxproj.filters
@@ -18,5 +18,13 @@
     <ClCompile Include="main.c">
       <Filter>Quelldateien</Filter>
     </ClCompile>
+    <ClCompile Include="book.c">
+      <Filter>Quelldateien</Filter>
+    </ClCompile>
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="book.h">
+      <Filter>Headerdateien</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/Demonstration/book.c b/Demonstration/book.c
new file mode 100644
index 0000000..02d215c
--- /dev/null
+++ b/Demonstration/book.c
@@ -0,0 +1,35 @@
+#include "book.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+Book* book_create(const char* title, const char* author, int year)
+{
+	// initialize book
+	Book* book = calloc(1, sizeof(Book));
+	if (!book)
+	{
+		return NULL;
+	}
+
+	// initialize title and author
+	book->title = calloc(strlen(title), sizeof(char));
+	book->author = calloc(strlen(author), sizeof(char));
+	if (!book->title || !book->author)
+	{
+		return NULL;
+	}
+
+	strcpy(book->title, title);
+	strcpy(book->author, author);
+	book->year = year;
+
+	return book;
+}
+
+void book_print(const void* data)
+{
+	const Book* book = (Book*)data;
+	printf("Book[title=%s,author=%s,year=%d]\n", book->title, book->author, book->year);
+}
\ No newline at end of file
diff --git a/Demonstration/book.h b/Demonstration/book.h
new file mode 100644
index 0000000..a43be45
--- /dev/null
+++ b/Demonstration/book.h
@@ -0,0 +1,11 @@
+#pragma once
+
+typedef struct {
+	char* title;
+	char* author;
+	int year;
+} Book;
+
+Book* book_create(const char* title, const char* author, int year);
+
+void book_print(const void* data);
\ No newline at end of file
diff --git a/Demonstration/main.c b/Demonstration/main.c
index 330d7c7..52e2bb7 100644
--- a/Demonstration/main.c
+++ b/Demonstration/main.c
@@ -1,45 +1,9 @@
 #include <stdlib.h>
 #include <stdio.h>
-#include <string.h>
 
 #include "../Implementation/linked_list.h"
 #include "../../MenuLib/menu.h"
-
-typedef struct {
-	char* title;
-	char* author;
-	int year;
-} Book;
-
-Book* book_create(const char* title, const char* author, int year)
-{
-	// initialize book
-	Book* book = calloc(1, sizeof(Book));
-	if (!book)
-	{
-		return NULL;
-	}
-
-	// initialize title and author
-	book->title = calloc(strlen(title), sizeof(char));
-	book->author = calloc(strlen(author), sizeof(char));
-	if (!book->title || !book->author)
-	{
-		return NULL;
-	}
-
-	strcpy(book->title, title);
-	strcpy(book->author, author);
-	book->year = year;
-
-	return book;
-}
-
-void book_print(const void* data)
-{
-	const Book* book = (Book*)data;
-	printf("Book[title=%s,author=%s,year=%d]\n", book->title, book->author, book->year);
-}
+#include "book.h"
 
 void show_push(Node** list)
 {
@@ -85,7 +49,7 @@ void show_insert(Node** list)
 	printf("Enter place after which book is inserted: ");
 	scanf_s(" %d", &index);
 
-	list_insert(list_get(list, index), book_create(title, author, year));
+	list_insert(list_get(*list, index), book_create(title, author, year));
 }
 
 void show_print(Node** list) 
@@ -98,7 +62,7 @@ void show_get(Node** list)
 	int index;
 	printf("Enter place: ");
 	scanf_s(" %d", &index);
-	list_print(list_get(list,index), &book_print);
+	list_print(list_get(*list,index), &book_print);
 }
 
 void show_remove(Node** list)
@@ -106,7 +70,7 @@ void show_remove(Node** list)
 	int index;
 	printf("Enter place: ");
 	scanf_s(" %d", &index);
-	list_remove(list_get(list, index));
+	list_remove(list_get(*list, index));
 }
 
 
@@ -121,7 +85,7 @@ void main(void)
 		{"Print item", '4', (void*)&show_print, &list},
 		{"Look at item by index", '5', (void*)&show_get, &list},
 		{"Remove item by index", '6', (void*)&show_remove, &list},
-		{"BLANK", NULL, NULL, NULL},
+		{"BLANK", ' ', NULL, NULL},
 		{"Quit", 'q', (void*)&exit, NULL}
 	};
 	struct MenuPage pages[] = {